Vacancy-type defects in Mg-doped GaN grown by ammonia-based molecular beam epitaxy probed using a monoenergetic positron beam

Uedono, Akira; Malinverni, Marco; Martin, D.; Okumura, Hajime; Ishibashi, Shoji; Grandjean, N.

doi:10.1063/1.4954288

Cited by 9 publications

(8 citation statements)

References 42 publications

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“…It should be mentioned that perfect lattice semiconductors are expected to have L eff in the range 200-300 nm [29]. The longest effective positron diffusion length L eff = 92 ± 3 nm for GaN was obtained for a hydride vapor phase epitaxy (HVPE) GaN [30]. By comparing their experimental (S, W) results with the theoretically calculated one, the authors concluded that the HVPE-GaN sample is defect free.…”

Section: Positron Annihilation Datamentioning

confidence: 98%

Study of Edge and Screw Dislocation Density in GaN/Al2O3 Heterostructure

et al. 2019

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This study assesses the characteristics (edge and screw dislocation density) of a commercially available GaN/AlN/Al2O3 wafer. The heterostructure was evaluated by means of high-resolution X-ray diffraction (HR-XRD), high-resolution transmission electron microscopy (HR-TEM), and Doppler-Broadening Spectroscopy (DBS). The results were mathematically modeled to extract defect densities and defect correlation lengths in the GaN film. The structure of the GaN film, AlN buffer, Al2O3 substrate and their growth relationships were determined through HR-TEM. DBS studies were used to determine the effective positron diffusion length of the GaN film. Within the epitaxial layers, defined by a [GaN P 63 m c (0 0 0 2) || P 63 m c AlN (0 0 0 2) || (0 0 0 2) R 3 ¯ c Al2O3] relationship, regarding the GaN film, a strong correlation between defect densities, defect correlation lengths, and positron diffusion length was assessed. The defect densities ρ d e = 6.13 × 1010 cm−2, ρ d s = 1.36 × 1010 cm−2, along with the defect correlation lengths Le = 155 nm and Ls = 229 nm found in the 289 nm layer of GaN, account for the effective positron diffusion length Leff~60 nm.

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Section: Positron Annihilation Datamentioning

confidence: 98%

Study of Edge and Screw Dislocation Density in GaN/Al2O3 Heterostructure

et al. 2019

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“…Till now, Mg has proven to be the most efficient p-type dopant despite of its high activation energy which requires a large amount of Mg concentrations (around 10 19 cm −3 or more) to be incorporated in order to achieve reasonable free hole concentrations close to 10 18 cm −3 . Any increase in Mg atomic concentrations beyond 10 19 cm −3 lead to a decrease in the free hole concentration [9–11]. This phenomenon is mainly attributed to the creation of N vacancies [12–14], Mg-related point defects [10, 15], or Mg vacancies-related charged and/or neutral complexes which lowers the Fermi level and saturates free hole concentrations [16, 17].…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Defects in Mg-Implanted and Mg-Doped GaN Layers on Freestanding GaN Substrates

et al. 2018

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Inefficient Mg-induced p-type doping has been remained a major obstacle in the development of GaN-based electronic devices for solid-state lighting and power applications. This study reports comparative structural analysis of defects in GaN layers on freestanding GaN substrates where Mg incorporation is carried out via two approaches: ion implantation and epitaxial doping. Scanning transmission electron microscopy revealed the existence of pyramidal and line defects only in Mg-implanted sample whereas Mg-doped sample did not show presence of these defects which suggests that nature of defects depends upon incorporation method. From secondary ion mass spectrometry, a direct correspondence is observed between Mg concentrations and location and type of these defects. Our investigations suggest that these pyramidal and line defects are Mg-rich species and their formation may lead to reduced free hole densities which is still a major concern for p-GaN-based material and devices. As freestanding GaN substrates offer a platform for realization of p-n junction-based vertical devices, comparative structural investigation of defects originated due to different Mg incorporation processes in GaN layers on such substrates is likely to give more insight towards understanding Mg self-compensation mechanisms and then optimizing Mg doping and/or implantation process for the advancement of GaN-based device technology.

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“…the doped samples, as the lattice state, surface state, and Ga vacancy state are almost aligned as is typical of GaN [27][28][29][30]. Hence the only conclusion that can be drawn from the (S, W) plot in Fig.…”

Section: Resultsmentioning

confidence: 88%

Interfacial N Vacancies in GaN /( Al<

Prozheeva

Makkonen

et al. 2020

Phys. Rev. Applied

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We show that N-polar GaN/(Al, Ga)N/GaN heterostructures exhibit significant N deficiency at the bottom (Al, Ga)N/GaN interface, and that these N vacancies are responsible for the trapping of holes observed in unoptimized N-polar GaN/(Al, Ga)N/GaN high electron mobility transistors. We arrive at this conclusion by performing positron annihilation experiments on GaN/(Al, Ga)N/GaN heterostructures of both N and Ga polarity, as well as state-of-the-art theoretical calculations of the positron states and positronelectron annihilation signals. We suggest that the occurrence of high interfacial N vacancy concentrations is a universal property of nitride semiconductor heterostructures at net negative polarization interfaces.

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Vacancy-type defects in Mg-doped GaN grown by ammonia-based molecular beam epitaxy probed using a monoenergetic positron beam

Cited by 9 publications

References 42 publications

Study of Edge and Screw Dislocation Density in GaN/Al2O3 Heterostructure

Study of Edge and Screw Dislocation Density in GaN/Al2O3 Heterostructure

Comparative Analysis of Defects in Mg-Implanted and Mg-Doped GaN Layers on Freestanding GaN Substrates

Interfacial N Vacancies in GaN /( Al<

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